# Copyright 2022 99Cloud, Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from __future__ import annotations

import collections
import importlib
import os
import pkgutil
from types import ModuleType
from typing import Any, List, Tuple

LIST_OPTS_FUNC_NAME = "list_opts"


def _tupleize(dct: collections.defaultdict) -> List[Tuple[str, Any]]:
    """Take the dict of options and convert to the 2-tuple format."""
    return [(key, val) for key, val in dct.items()]


def list_opts() -> List[Tuple[str, Any]]:
    opts: collections.defaultdict = collections.defaultdict(list)
    module_names = _list_module_names()
    imported_modules = _import_modules(module_names)
    _append_config_options(imported_modules, opts)
    return _tupleize(opts)


def _list_module_names() -> List[str]:
    module_names = []
    package_path = os.path.dirname(os.path.abspath(__file__))
    for _, modname, ispkg in pkgutil.iter_modules(path=[package_path]):
        if modname == "opts" or ispkg:
            continue
        else:
            module_names.append(modname)
    return module_names


def _import_modules(module_names: List[str]) -> List[ModuleType]:
    imported_modules = []
    for modname in module_names:
        mod = importlib.import_module("dandelion.conf." + modname)
        if not hasattr(mod, LIST_OPTS_FUNC_NAME):
            msg = (
                "The module 'dandelion.conf.%s' should have a '%s' "
                "function which returns the config options." % (modname, LIST_OPTS_FUNC_NAME)
            )
            raise Exception(msg)
        else:
            imported_modules.append(mod)
    return imported_modules


def _append_config_options(
    imported_modules: List[ModuleType], config_options: collections.defaultdict
) -> None:
    for mod in imported_modules:
        configs = mod.list_opts()
        for key, val in configs.items():
            config_options[key].extend(val)
